Collagen is the major protein of connective tissue and changes in the deposition of collagen may occur in several disease states such as lung dust disease and arteriosclerosis. In that these changes may represent alterations in the normal control mechanisms involved in collagen synthesis the long range goal of this project is to add to our understanding of what these control mechanisms are and how they may be altered. The immediate objectives are: (1) to characterize the effects of growth conditions known to alter the amounts of collagen synthesis, (2) to develop a system in which the type of collagen synthesized may be changed. We will employ medium hypertonicity as a means of altering the amount of collagen synthesized by cultured chick embryo bone cells, and treatment with 5-bromodeoxyuridine, embryo extract, or hypertonicity to change the type of collagen synthesized by cultured embryonic chick chondryoctyes. The methods employed will primarily involve the use of polyacrylamide gel electrophoresis and collagenase digestion in studying the amounts of collagen produced and cyanogen bromide peptide analysis to characterize the types of collagen synthesized.